CA2122804A1 - Single step developable negative working and positive working printing plate and imaging process - Google Patents
Single step developable negative working and positive working printing plate and imaging processInfo
- Publication number
- CA2122804A1 CA2122804A1 CA002122804A CA2122804A CA2122804A1 CA 2122804 A1 CA2122804 A1 CA 2122804A1 CA 002122804 A CA002122804 A CA 002122804A CA 2122804 A CA2122804 A CA 2122804A CA 2122804 A1 CA2122804 A1 CA 2122804A1
- Authority
- CA
- Canada
- Prior art keywords
- coating
- plate
- negative
- positive
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/004—Photosensitive materials
- G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
- G03F7/095—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having more than one photosensitive layer
- G03F7/0952—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having more than one photosensitive layer comprising silver halide or silver salt based image forming systems, e.g. for camera speed exposure
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Photosensitive Polymer And Photoresist Processing (AREA)
- Manufacture Or Reproduction Of Printing Formes (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Printing Methods (AREA)
Abstract
ABSTRACT
A lithographic printing plate precursor and process for its utilization have been discovered through which negative and positive original images can be printably reproduced on the plate precursor in substantially fewer development steps. The precursor plate is exposed sequentially to either the negative or positive original with the resultant image subsequently developable in a single process or step. The process is achieved by using a precursor plate having two coatings of significantly different photographic sensitivity to light, i.e., speed as characterized by "camera speed" or "contact speed" and imagewise exposing the originals in sequence to alternative speeds. The contact speed coating may be negative-working or positive working while the camera speed coating is negative-working. The camera speed coating is developed followed by exposure of the contact speed coating. Images produced at camera speed are removed and non-image bearing portions; of the contact speed coating are removed. The remaining image areas corresponding to the negative and positive originals are treated to provide positive printable images.
A lithographic printing plate precursor and process for its utilization have been discovered through which negative and positive original images can be printably reproduced on the plate precursor in substantially fewer development steps. The precursor plate is exposed sequentially to either the negative or positive original with the resultant image subsequently developable in a single process or step. The process is achieved by using a precursor plate having two coatings of significantly different photographic sensitivity to light, i.e., speed as characterized by "camera speed" or "contact speed" and imagewise exposing the originals in sequence to alternative speeds. The contact speed coating may be negative-working or positive working while the camera speed coating is negative-working. The camera speed coating is developed followed by exposure of the contact speed coating. Images produced at camera speed are removed and non-image bearing portions; of the contact speed coating are removed. The remaining image areas corresponding to the negative and positive originals are treated to provide positive printable images.
Description
2~28~
~G~ P DBVE~OP~B~B ~ ~D
PO~ITI7~ ~Q~KI~ P~I~TI~ ~L~T~ ~D I~A~ 2~0C~8&
This invention relates to a lithographic printing plate which can be employed in the production o~ positive imayes fro~ negative and positive origi~als. The inven-tion also relates to a pro ~5~ ~or the formation ~f printable images on a lithographic plat~ from negative and positive originals employing a single development step. More pecifically, the inv~ntion relates to a printiny plate having a silver halide coating and a non-RilYer halid~ coating and to a proce~ for producing printable images from negativ~ and po~itive origi~als.
The prepress operations associated with lithographic printing plate production are de~anding and becoming increasingly complex. Dependi~g on the demands and preferences of the customer, printer~ may be required to use both negative and positive ori~inal transparencies as the i~put material~ to produce a ~inished plate.
Additionally, the high quality of t~e finish~d plate must be maintained regardless of the type of original input ~nd must be commensurate with the need to produce copies that may number in the millions. However, as a con$equ~nce of thes2 incr~asing requirements, both unipolar and bipolar plates are now available to the printing industry so that a single negative or positiv~
original (unipolar) or both negative and positive originals (bipolar3 can be used a~i input for printing plate image production. Rnown unipolar plates comprise ge~rally a single photosensitive layer on a hydrophilic substrate. Rnown bipolar plates comprise g~nerally at least two photosensitive layers on a hydrophilic substrate and are known in the art as bilevel plates, :
referring to the two photosensitive layersO
Currently, if the printer uses a conventional - unipolar plate such as a negative working or a positive working plate to reproduce a negative and a positive original, i.e., bipolar reproduction, one o~ the original input matsrials must be converted to suit the final plate mode. This is expensive and time consuming. If the printer resorts to the use of a bipolar plate as available in the art heretofore for reproduction of images from negative and positive originals, additional process steps in development, masking or exposure are invariably re~uired which renders this alternatiYe expensive and time consuming as well. The additional steps required in the present art of bipolar printing plate utilization flow from the fact thak in order to obtain the reyuisite positive images on the final printing plate from a negative and a positive original input, a reversal of one of the original images needs to be accomplished during the photc)graphic image transfer 2~ocess.
Artisans .in the photograph.ic arts have ~ound the problem of simplifying the production and lowering the cost of a lithographic printing plate produced from negative and positive originals to b~ a substantial challenge. A major objective o~ the instant invention is :~ :
to effectively meet that challenge.
U. S. Pat~nts 4,576,901 and 4,581,321 disclose a process for p~oduc.in~ negative copies by imagewise ~xposing a coating containing amide sub~tituted 1,2-quinone diazides followed by heating, re exposing and developing. The process permits the production of negative copies with the aid o~ a material which yields positive copies when it is processed in a conventional manner. ~ ~`
~12~
....
U~ S. Patent 4,927,741 discloses a proces~ and apparatus fDr reversal proceisising to produce a negative of an original image on the plate. The printing plates is required to be exposed overall after heating. Exposure is carried out while the plate is conveyed through wat~r.
U. S. Patent 4,299,912 discloses a process ~or producing a lithographic printing plate using a plate containing two light sensitive layers, one of which is a gelatin-silver halide emulsion and the vther is a non-silver halide layer. The patent teaches the use of a proteolytic enzyme to aid in the removal of the gelatino layer after imagewise exposure followed by exposure o~
the no~-silver halide layer, U. S. Patents 4,341,856 and 4,283,478 teach printing plates containing at least two light sensitive layers.
Production of the ~inal image containing printing plate entails at least two exposure steps.
U~ S. Patents 4,350,753 and 4,348,471 incorporated by reference teach positive acti.ng printiny plates having high pre-development image visibility, including positive coatings consisting of phenolic--No~olak resiins. U. S.
Pat~nt 3,635,709 incorporated he.rein by reference, teaches a positive acting lithographic printing plate wherein the light sensitive layer is a composition :;
comprising an ester of 2-diazo-l-naphthol-4 (or--5)~
sulfonic asid with a polyhydroxy phenol that is a condensation product of acetone and pyrogallol. ;~
U. S. Patent 3,567,445 incorporated by re~erence -;~
teaches a presensitized lithographic printing plate with :
two differentially æpectrally sensitive layers separated ;
by a Novolak resi~. The base layer i~ o~ the type used in a negatlYe~working presensitized lithographic plate while the top layer is a silver halide emulsion layer.
~22g~
~, ., It i~3 an ob~ 3n~ t~
or ~itigate at lea~t o~e og~ th~ abov~ ntioned di~adYantages of the prior art~
A~3 e~ploy~ h~r~ , thQ t~ printing pl~t~
pr~curso3: re~ers ts:~ a hydrophilic ~ubstrate having on~ or more 1 ight ~ensitive cc>atingE~ or lay~r~, The precur~or plate i~ u~ed to produce a lithoqraphlc prirltirlg plate 15 use:Eul in printing opera~ions.
A lithographic printing p'Late precur~or and proce~e~
for it3 utilizatlon hav~ b~en d L~cov~3red through which negative and po~itiv~3 oriyina;L imag~ can be printably 20 reproduc~d on the lplate pr~c:urlscr in sub~;tantially ~ewer dev~1OpmQnt ~t~p~. ThQ precurlsor plat~ i~ expo~;ed sequenti~11y to either the negati~ or positive origina1 with the rQ~ulkant iD: ag~3 ~ubsequent1y dev210pab1e in ~
sin~1e proc~ or step. ~he procssY is a<:hievQd by u~ing 25 a precurst:3r 1p1ate having two coati~gs o~ significarst1y di~f~rent photographi¢ sensi1:ivity to 1ight, i . e., æpeed a~ cha~acterix~d by "camera s~p~d" or "co~atac:t spe2dN and i~ag~wisQ exposing the orig1na1~3 in ~guence to ~ ~
alternative sped~. T21~3 contact sp~d ::oatiny may be : .
30 n~gative~workirl~ or po~itive working whi1e ths c~mera ~peed coating is neyativ~-~orking. Th~ came:ra clpeed coa~ is deve1Oped fo11Owed by Qxpo~ure o~ the contact spe~d coating. Images produced at camera ~peedi are r@moved and no~ Aa~e bearing portions of the contact . .
speed coating are removed. The remaininy image are~
corresponding to the negative and positiYe oriqinals are treated to provide positivQ printable images.
More particularly, a proces~ ~or producing a negative original image and a positive original image on a printing plate employing a single development step has been discovered. The proces~ comprises providing a coated printing plate comprising a substrate having coated thereon a first positive-working, non-silver halide, light sensitiYe coating photoinsensitive to light at silver halide speeds and a second or top negative-working coating comprising silv~r halide emulslon. A first ~:
poxtion of the plate is exposed image-wise through a posîtive original at a high exposure speed, i.e. contact speed, sufficient to expose the first coating and second coating. Then, at a low exposure speed, i.e., camera sp~ed, both a second portion of said plate is exposed image-wis~ through a negativ~ original with nonimage-wise exposure of the ~irst portion from the foregoing positive origi~al image-wise exposure. 'rhe top coating ie then developed. Next, the plate is subjected to an overall exposure at high exposure speed. The plate is then ~ .
treated to remove exposed and unexposed residue of the ~ ;
second or top coating followed by treatment of the first coating to remove non-image containing areas of the first coating whereby a printing plate is prQduced containing images corresponding to the negative and positive originals.
In the process of the invention~ the first coating may be a positive-working or a negative-working coating while the top or second coating is a negative working coating. The proces~ o~ the invention ~or a plate having ~ -~
both the first and second coating negative-working proceeds as ~ollows or a bilevel printing plate :~
comprising a substrate having coated thereon a first 2 1 22~
negative-working, non-silver halide, light sensi~ive coating photoinsensitiYe to light at silver halide speeds and a second or top negative-working coating comprising silver halide emulsion.
At a low exposure speed, both a first portion of the plate is exposed image-wise through a positiv~
original with nonimage-wise exposure o~ a second portlon o~ plate. Then, at a high exposure speed second portion ii exposed image-wise through a negative origi~al. The top coat is de~eloped followed by oversll ~xpo6ure of the plate at a high exposure speed. The plate is then treated to remove exposed and unexposed residue of said ~op coating and further treated to remove non-image containing areas of the first coating whereby a printing plate is produced containing images corresponding to the negative and positive originals.
For koth procesies described herein, the order of exposure, i.e~, poiitive origin2l1 Pirst or nega~ive original first is nDt critical. Either original may be exposed first.
The invention also includes a presensitized printing plate for seguentially producing a negative original image and a positive original image on a printing plate employing a singl~ development step. The plate comprises 2~ a substrate having coated th~reon a firit non ~ilver halide, light sensitive coating photoinsensiti~e to light at silver halide exposure speeds and a second or top -~
coating comprising iilver halide emulsion, wherein the irst coating is selected from the group consisting of diazo r~sins, diazide compounds, azide compounds, polymers having alpha, beta un~aturated carbonyl compounds in the main or side chain, and unsaturated monomers photopolymeriæable by addition polymerization.
2 ~
The lithogr~phic print~n~7 plate pr~cur~or o~
pre~ent inverltio3l co~pris~ a ~uppe~ r ~ rate upon which i~ coa~ed a ~ir~t coa~ing comlpri~ g a nonosilvex 5 halîde cs~ting ~en~itive to light alt ::o~tact ~sq?osure speeds and a ~econd or top coatirlg c:omprising a s~lver halid~ emulsion ~enE~itivQ to lighit al: ca~era e~ sur~
~peed8 .
The te~ '~ mera ~p~d~3 ~nd "high sp~3ed' ar~ ~ nter-10 changeably used herein. "Camera ~pQad~ or "high speed"mear~s that the coating i5 su~fici~ntly fa~t, i.e., photo-graphically light sensitive, to be usad in a camera ~uch a~3 a proce~;s camera and embodi~ focusing an origirlal onto the light s~en~itiv~ layer throu~h an image-foc:usi~lg 15 len~. ~ high expo~ure E~pe~d or camQr~ sp2ed co~ting in thQ pr~sent inv~ntion h~b expo~ur~ speed~ betw~en 1 and 2û millijoules per 3quare cen~.imç~ter (m~ but prsîerably about 5 ~j/CDIZ. For camera ~peed or high ~p~d c:c3at~ngs a comparatively lc~w ell~r~ level o~ light 20 i~ all thal: i~ requlred to impinge upon the coating to produce a lighlt induced che~iaal changa in th~3 coating and a corre~ponding photograpPIic ef~ect~ "Contact pe~d'g, sar low ~xpoaur2 8pelBSl a~ u~ad herein, ~e~ns that a light ~ensitiv~ materi~l can b~ exposed through a 25 po~itiv~ or n~g3.tiv~ transpar~ncy original placed in contact with it. Contact ~3pe~d coating~ used in the pre6ant inYention have speedis betwes~n about 200 and 1000 mj/cm2, bllt pr~ferably about 400 mj/cm~. Cor~tac:t expo~ure ~peed or low sps~d coatings re~auire 30 i3ub~t~ntially high~r ~nergy l~vel~3 o~ light to impinsle uporl ~he coating lto produc6l! a ch~r~ic~l change in th~ :
coating and a corresponding photc~raphic ~ffectO
The ~upport or substrate ~or the printing plate prerursor o~ the invention Diay b~ any of tho~ supports 35 or ~ubstratr2s having ~ hydrophilic ~ur~ace that are commonly u~ed as supports in the manu~acture o~ printing plates. Examples include hydrophilic metal plates such as aluminum, composite metal plate6, plastic films, pap~r and the like.
The Pirst coating on the ~ubstrate which compri~es a non silver halide coating ~ensitive to light at contact speeds yields a lipophilic image and includes light sensitive coatings conventionally used in light sensitive lithographic printing plates. The term lipophilic means that the image repels water for wetting in printing and receives oily ink. ~xamples o cumpositions constituting such light sensitive coatlngs are described in U. S.
Patent 4,299,912 and in the patents assigned to Polychrome Corp. and incorporated by reference herein before. They include by example without limitation-Compositions comprising one or more diazo resins;
composikions comprising one or more o-naphthoquinone-diazide compounds; compositions comprising one or more light sensitive azide compounds) compounds comprising one or more polymers containing an alpha, bata unsaturated carbonyl group in the main or s:ide chain thereof; and photopolymeri~able compositions comprising one or more addition polymeri~able unsaturated compounds.
As used herein, by light sensitive ~irst layer or coating capable of being used as th~ light sensitive layer in a negative-working presensitized printing plate is meant a layer which can be coated onto the base and which is sensitive to light such as ultra-violet light and when exposed to such through a negative in the exposed areas undergoes goes a chemical reaction which renders the exposed areas insolubl~ laaving the unexpoeed areas dissoluble. By light sensitive first layer or co~ting capable of being used as the light sansitive layer in a positive-working presensitized printing plate is meant any liyht sensitive composition that is 2~.~2~
~9_ sensitive to light such as ultraviolet light and when ~ exposed to such light undergoes a chemical reaction in the expos~d areas whereby the exposed areas become s41uble and removablP.
A~ example of a positive working resin composition which can be developed with an alkaline solution is one which contains a light sensitive material such as o-naphthoquinonediazide. Examples o~ negative working resin compositions which can be developed following UV
light exposure include polvinylcinnamate, vinyl polymeris containing an aromatic azide group and the li~e. The photographic speed o~ these compounds is too slow ~sr ~
plates sensitized therewith to be o~ camera speed and ~ ~X
thus, as previously ~tated, mo~t presensitized lithoyraphic plates are of contact ipeed.
U. S. Patents 4,483,758 and 4,447,512 incorporated herein by reference, teach nega1ive working co~positions consisting of diazo resin based on diphenyl amine sulfate condensate with formaldehyde an~l isolated as 2-hydroxy-4 methoxy-benzophenone-5-sulfonic acid salt. Also included ~;
are polymers with alpha, beta unsaturated carbonyl groups in the main or side chain.
The top layer or coating o:E the lithographic plate ~ :~
precursor o~ the invention comprises any type of gelatin-silver halide emulsion depending on the original to ~e produced. Silver halide includes silver chloride, silver bromide, silver iodide and mixtures thereof as conventionally employ~d in the art. The average silver halide grain diameter is preferably between O.Ol~i and 5 In oxder to provide a suitable or desired sensiti~ity to the silver halide, the grains thereof can be subject to chemical sensitization, eOg., sul~ur sensitization, reduction sensitization, sensitization ~,"~ , "".~" ~. ~,,.
2~2~
--lo~
using salts of noble metals such as Ir, Rh, Pt, etc., or speGtral sensitizatiQn using ~ensitizing dyes. Silver halides o~ the latent sur~ace image type and inner latent image type can be used. The silver halide emulsion generally contain various additives as known in the art.
The gelatin-silver halide light sensitive emulsion layer i5 provided so that the dry weight is about 1 to about 10 g/mZ, preferably from 2 to 6 g/m2.
The invention comprises a process to prcvide a :~
n bilevel printing plate precursor that can ba developed in one step or stage to produce positive, printahle images from both negative image input and positive image input material. ~
Positive-workin~ Plate ~ith ~egLative-workinq Emulsion ~:
A preferred embodiment comprises a six-step process.
A presensitized printing plate is provided containing a ~irst positive-working light sensitive resin coatingO
The printing plate is then coated with a second coating comprising a negative-working liLght sensitive silver halide emulsion to provide a bileYel plate. The six process step~ are carried on the bilevel plate.
In a first step, a first portion of the printing plate is exposed throuqh a positive original at a high light energy level (about 400 mj/cm2). The exposur~
results in a conversion of a corresponding portion of the silver halide emulsion to latent sil~er image and a conversion of a corresponding portion of the light sensitive r~sin to an alkali solubl~ resin. The unexposed area corresponds with the positive image in both the top ~nd first coating.
In the next step; a second portion of the plate is exposed through a negative original at a substantially - 2~22~ ~
lower light energy 12vel (about 5 mj~cm2) and the positive exp~sed first portion o~ the plate is also exposed to the same low light energy level, thereby blocking or prot~cting the unexposed portion of the f.irst coating in the first portion of the plate. Optionally, the positive exposed first portion of the pla~e can be masked and subsequently exposed to lower light energy level but it is preferred to carry out an overall ~xposure. This step creates a latent image of the neyativ~ original in the emulsion on the second portion : :
of the plate while the unexpos~d portion of the emul~ion on s~id first portion is also expos~d. The low energy level is too low to convert the resin coating.
~: `~ .' The lentire plate is processed in a developer to develop the negative latent image in the emulsion o~ the second portion of the plate and the fogged area of the emulsion of the first portion. The developed negative image is fixed, resultin~ in removal of silver halide in the second portion area while metallic silver in the first and second portions of the~ emulsion remain unchanged. This step provides a silver coating in the top layer protecting the first portion overall and thus the unexposed porkion of the first layer corresponding to the po~itive original image. In a~dition, a silver coating in th~ second portion which corresponds to the neyative original image area covers or protects the ~irst coating from subse~uent expo~ure.
After the development step, the entire area o~ the plate is preferably exposed overall to a high light energy level of about 400 mj/cm2~ The exposur~ results in the conversion or exposure o~ the resin und2rneath the emulsion on the second portion of th plat~ except for that area of the resin directly underneath th~ image produced in the emulsion ~rom the negative exposure.
2 ~
.. ...
Following overall exposure at high exposure speed the emulsion layer i removed by washing or o-ther means well known to those skilled in the art l aving the resin layer containing exposed resin in the first and second portions and unexposed resin corresponding to the positive and negative image in the first and second -portion of the plate. ~
Next, the exposed resin areas which contain, in one ~ .
embodiment, carboxyliG acids produced by exposure to light are removed by alkali treatment leaving only the :
resin containing area~ corresponding to the positive and negative images~ These areas are further processed by means ~nown in the art such as heating to harden (baking), QtC, for printing.
The process can be carried out by first exposing the plate to negative original input followed by positive input. For that option the process is modified to comprise a first image-wise exposing of a first portion of the plate through a negative original with nonimage-wise exposing the second portion at low exposure speed sufficient to expose the second coating only. The nexk st~p comprises image-wise expos:ing the second portion using the positive original at high exposure speed sufficient to expose the first and second coating.
Subsequent processing follows the d2velopment, post-exposure and treatment steps described above.
Neqative-workinq Plate with NeaativP-workinq Emulsio~
Another preferred embodiment of the invention is to employ a presensitized printing plate having a first negative-working light sensitive resin coating. The printing plate is then coated with a second coating comprisin~ a negative-working light sensitive silver halide emulsion to provide a bilevel plate. The process steps in this embodiment are depicted as ~ollows for :~
' ,,:
,~ 2 ~ ~fJ r;~
:
initial optional ~xposure thro~lgh a positi~ve original:
Exposing at a low exposur~ speed both a ~irst portion of thP plate image-wisa through a pQSitiVe original and no~image-wise exposure of a second portion ::
of said plate. This provides a latent image overall on the second coating except for that portion of the ~irst portion corresponding to the positive image.
Next, exposing at a high exposure sp2ed the second portion image-wise through a negative original. This convert~ the first coating as well as converting the second coating to latent silver image, both in an area corxesponding to the negative image.
Following this, the entire plate is processed in a developer to develop the negative latent image in the emulsion of the first portion oiE the plate and the ~ogged area o~ the emulsion of the second portion. Thi~ step provides a silver coating in the top layer protecting the first portion non-image area and thus the unexposed portion of the first layer corr~sponding to the non-image area of the positive original. :rn addition, a ~ilver ~ :~
coating in the second portion overall prot~cts the firi~t coating non-image area from subsequent exposure. -~
A~ter the development step the entire area of the plate is pr~erably ~xposed overall to a high light energy level of about 400 mj/cm2. The exposure results in the conversion or exposure of the resin underneath the ~::
second coating on the first portion of the plate except ~or that non-image ~rea of the resin protected by metallic silver porti~n~ of the second coating.
Following overall exposure at high exposure speed the emulsion layer is removed by washing or other means well known to those skilled in the art leaving thP resin - 2 ~
~14~
layer containing unexposed re~in in the first and second portions and exposed resin corr~sponding to the positive and negative imaye in the ~irst and second portion o~ the ~:
plate.
Next, the unexposed resin ar~as are removed by ~` .
leaving only the re~in containiny areas corresponding to the positive and negative images. These areas are :~
further processed by means known in the art such as heating to harden, etc, for printing.
Here again th~ order of exposure of the plate comprising a negative-working first coat with negative-working top coat can be varied to expose the plate through a negative original fir~t at low exposure speed rather than through a positive original at low expo~ure speed. This variation o~ the process proceecls as follows:
Exposing image-wise at a high exposure speed through a negative original a first por1;ion o~ the plate and then exposing at a low expo~ure speecl both the second portion of said plate image-wise through a positive original and nonimage-wiss exposure of the flrst portion of the plate.
Subsequent proces~ing follows the development, post-exposure and treatment steps described above for the negative-working first coating and negative-working second coating case.
The following Examples 1 4 describe various embodiments o~ the present invention:
. .
Example 1 :
Polychrome positive plate T-40, described in U. S. ~:
paten~s 4,350,753 and 4,283,478, wa~ overcoated by a ::
"roomliyht" handling silver halide negative emul~ion, Polychrome DLC, day light contact emulsion useful under white light conditions. The plate was exposed for 5 :., mj~cm2 in contact with a negative original using a Berkey Ascor exposure frame. Part of the area not covered by the ne~ative was contacted with a positive trangp~rency while the area of the plate previously cov~red by the 5 negative original was maslced to avoid ;econdary exposure. - `
An expo~ure of 400 m~/cm2 was then given to the plate.
The plate was then processed i~ a rapid access silver halide development solution (b~tch developer PRB 127) ~or negative or positive emul~ions, and Polychrome fixer PF200. Th~ plate was then given overall W exposure, silver emulsion was removed by warm water and processed in conventional positive plate chemistry , i.e.
Polychrome's positive developer 3000 and Gum Pcs63~ The plate exhibited excellent positive image both ~rom the negative original portion and positive original portion.
Example 2 Polychroms positive plate known as 7'Posimatte", described in U. S. patents 4,350,753 and 4,~83,478, was overcoated by Polychrome silver halide emulsion PQF. The plate was exposed on the opticOpy Imposer II (Polychrome System Inc.) using negative transparency as originals with exposure ranging from l to lO seconds to the Imposer light source of pulsed Xenon lamps attenuated by a series o~ ~ilters to givs the ~reen portion of the light -~
spectrumO The expo~ed areas were fully masked by masking sheets. The open areas requiring positive transparency :~
input were contacted with the transparency and were given W exposure to fully expose Posimatte. The trans~
parency was rsmoved and the plate was briefly given an overall (visible light~ exposure to uniformly expose the :~:
coating not covered by the previous negative exposure.
The plate was then developed, fixed, re-exposed, emulsion removed and processed in positive plate developer to give a plate bearing positive image oP both negative input and positive input.
2 ~ ~ ~ 8 ~lj '1 Example 3 Polychrame positivQ plate T-40 was overcoated with Polychrome laser scann~r emulsi4n ~SF ~or ion-argon laser and ~ontaining sensitizing dys~. The plate was ~xposed on Gerber Scientific las~r exposing system LE 55 to give text portion of image in~ormation along with a blank expo~ur~ to the area whex~ the picture and graphic elements were to be inserted. The plate was th~n sxposed in contact with a masking sheet with picture and graphic elements pasted in. Following development, fixing, re- -exposure, washing and development, the plate exhibitsd both text and graphic elements ready for high guality printing.
Example ~
Polychrome negative working plate Vistar M, describecl in U. S. patents 4,483,758 and 4,447,512, is overcoated by a room light handling silver halide negative emulsion, DLC. The plate is exposed for 5.0 mj/cm2 in contact with a positive original using a Berkey Ascor exposure frame. Part of t:he area not covered by the positive is contacted with a negative transparency. An exposure of 400 mj/cm2 is given to the plat~, while the area of the plate previously covered by th~ positive original is masked to avoid secondary ~xposure. The plate is then processed in a rapid access silver halide development solution, i.e., PRB127, and further processed as in Example l.
. .
The progress in digital tec~nology enabled printers ;:~
to use digital direct platemaXers. ~igh speed of text ~:
printing provides considerable productivity improvements over thr convention~l analog mode o~ plat~ preparation. :~
In case o the graphics and pictures, however, the requirements for high level of memory and computing ~peed are such that the sy~tem becomes not only costly but slow to generate high quality images at reasonable speed.
2~22~
, ., ,~ .
".................................................................... :
-17~
The bimodal plate and the process proposed not only eliminates such inconvenience~ as additional film making but also improves productivity substantially by allowing various mode of transparenci~s and signals as the original inpu~. In conventional analog contact method, both negative and positive originals can produce equally excellent images. In case of digital application, high speed texts can be la er imaged while pre-prepared qraphics and picture eleme~ts can be contact exposed taking advantages of high speed digital generation of . .
texts and high rate of information transfer of prepared graphics o high memory requirements.
'~'''~.'`
~G~ P DBVE~OP~B~B ~ ~D
PO~ITI7~ ~Q~KI~ P~I~TI~ ~L~T~ ~D I~A~ 2~0C~8&
This invention relates to a lithographic printing plate which can be employed in the production o~ positive imayes fro~ negative and positive origi~als. The inven-tion also relates to a pro ~5~ ~or the formation ~f printable images on a lithographic plat~ from negative and positive originals employing a single development step. More pecifically, the inv~ntion relates to a printiny plate having a silver halide coating and a non-RilYer halid~ coating and to a proce~ for producing printable images from negativ~ and po~itive origi~als.
The prepress operations associated with lithographic printing plate production are de~anding and becoming increasingly complex. Dependi~g on the demands and preferences of the customer, printer~ may be required to use both negative and positive ori~inal transparencies as the i~put material~ to produce a ~inished plate.
Additionally, the high quality of t~e finish~d plate must be maintained regardless of the type of original input ~nd must be commensurate with the need to produce copies that may number in the millions. However, as a con$equ~nce of thes2 incr~asing requirements, both unipolar and bipolar plates are now available to the printing industry so that a single negative or positiv~
original (unipolar) or both negative and positive originals (bipolar3 can be used a~i input for printing plate image production. Rnown unipolar plates comprise ge~rally a single photosensitive layer on a hydrophilic substrate. Rnown bipolar plates comprise g~nerally at least two photosensitive layers on a hydrophilic substrate and are known in the art as bilevel plates, :
referring to the two photosensitive layersO
Currently, if the printer uses a conventional - unipolar plate such as a negative working or a positive working plate to reproduce a negative and a positive original, i.e., bipolar reproduction, one o~ the original input matsrials must be converted to suit the final plate mode. This is expensive and time consuming. If the printer resorts to the use of a bipolar plate as available in the art heretofore for reproduction of images from negative and positive originals, additional process steps in development, masking or exposure are invariably re~uired which renders this alternatiYe expensive and time consuming as well. The additional steps required in the present art of bipolar printing plate utilization flow from the fact thak in order to obtain the reyuisite positive images on the final printing plate from a negative and a positive original input, a reversal of one of the original images needs to be accomplished during the photc)graphic image transfer 2~ocess.
Artisans .in the photograph.ic arts have ~ound the problem of simplifying the production and lowering the cost of a lithographic printing plate produced from negative and positive originals to b~ a substantial challenge. A major objective o~ the instant invention is :~ :
to effectively meet that challenge.
U. S. Pat~nts 4,576,901 and 4,581,321 disclose a process for p~oduc.in~ negative copies by imagewise ~xposing a coating containing amide sub~tituted 1,2-quinone diazides followed by heating, re exposing and developing. The process permits the production of negative copies with the aid o~ a material which yields positive copies when it is processed in a conventional manner. ~ ~`
~12~
....
U~ S. Patent 4,927,741 discloses a proces~ and apparatus fDr reversal proceisising to produce a negative of an original image on the plate. The printing plates is required to be exposed overall after heating. Exposure is carried out while the plate is conveyed through wat~r.
U. S. Patent 4,299,912 discloses a process ~or producing a lithographic printing plate using a plate containing two light sensitive layers, one of which is a gelatin-silver halide emulsion and the vther is a non-silver halide layer. The patent teaches the use of a proteolytic enzyme to aid in the removal of the gelatino layer after imagewise exposure followed by exposure o~
the no~-silver halide layer, U. S. Patents 4,341,856 and 4,283,478 teach printing plates containing at least two light sensitive layers.
Production of the ~inal image containing printing plate entails at least two exposure steps.
U~ S. Patents 4,350,753 and 4,348,471 incorporated by reference teach positive acti.ng printiny plates having high pre-development image visibility, including positive coatings consisting of phenolic--No~olak resiins. U. S.
Pat~nt 3,635,709 incorporated he.rein by reference, teaches a positive acting lithographic printing plate wherein the light sensitive layer is a composition :;
comprising an ester of 2-diazo-l-naphthol-4 (or--5)~
sulfonic asid with a polyhydroxy phenol that is a condensation product of acetone and pyrogallol. ;~
U. S. Patent 3,567,445 incorporated by re~erence -;~
teaches a presensitized lithographic printing plate with :
two differentially æpectrally sensitive layers separated ;
by a Novolak resi~. The base layer i~ o~ the type used in a negatlYe~working presensitized lithographic plate while the top layer is a silver halide emulsion layer.
~22g~
~, ., It i~3 an ob~ 3n~ t~
or ~itigate at lea~t o~e og~ th~ abov~ ntioned di~adYantages of the prior art~
A~3 e~ploy~ h~r~ , thQ t~ printing pl~t~
pr~curso3: re~ers ts:~ a hydrophilic ~ubstrate having on~ or more 1 ight ~ensitive cc>atingE~ or lay~r~, The precur~or plate i~ u~ed to produce a lithoqraphlc prirltirlg plate 15 use:Eul in printing opera~ions.
A lithographic printing p'Late precur~or and proce~e~
for it3 utilizatlon hav~ b~en d L~cov~3red through which negative and po~itiv~3 oriyina;L imag~ can be printably 20 reproduc~d on the lplate pr~c:urlscr in sub~;tantially ~ewer dev~1OpmQnt ~t~p~. ThQ precurlsor plat~ i~ expo~;ed sequenti~11y to either the negati~ or positive origina1 with the rQ~ulkant iD: ag~3 ~ubsequent1y dev210pab1e in ~
sin~1e proc~ or step. ~he procssY is a<:hievQd by u~ing 25 a precurst:3r 1p1ate having two coati~gs o~ significarst1y di~f~rent photographi¢ sensi1:ivity to 1ight, i . e., æpeed a~ cha~acterix~d by "camera s~p~d" or "co~atac:t spe2dN and i~ag~wisQ exposing the orig1na1~3 in ~guence to ~ ~
alternative sped~. T21~3 contact sp~d ::oatiny may be : .
30 n~gative~workirl~ or po~itive working whi1e ths c~mera ~peed coating is neyativ~-~orking. Th~ came:ra clpeed coa~ is deve1Oped fo11Owed by Qxpo~ure o~ the contact spe~d coating. Images produced at camera ~peedi are r@moved and no~ Aa~e bearing portions of the contact . .
speed coating are removed. The remaininy image are~
corresponding to the negative and positiYe oriqinals are treated to provide positivQ printable images.
More particularly, a proces~ ~or producing a negative original image and a positive original image on a printing plate employing a single development step has been discovered. The proces~ comprises providing a coated printing plate comprising a substrate having coated thereon a first positive-working, non-silver halide, light sensitiYe coating photoinsensitive to light at silver halide speeds and a second or top negative-working coating comprising silv~r halide emulslon. A first ~:
poxtion of the plate is exposed image-wise through a posîtive original at a high exposure speed, i.e. contact speed, sufficient to expose the first coating and second coating. Then, at a low exposure speed, i.e., camera sp~ed, both a second portion of said plate is exposed image-wis~ through a negativ~ original with nonimage-wise exposure of the ~irst portion from the foregoing positive origi~al image-wise exposure. 'rhe top coating ie then developed. Next, the plate is subjected to an overall exposure at high exposure speed. The plate is then ~ .
treated to remove exposed and unexposed residue of the ~ ;
second or top coating followed by treatment of the first coating to remove non-image containing areas of the first coating whereby a printing plate is prQduced containing images corresponding to the negative and positive originals.
In the process of the invention~ the first coating may be a positive-working or a negative-working coating while the top or second coating is a negative working coating. The proces~ o~ the invention ~or a plate having ~ -~
both the first and second coating negative-working proceeds as ~ollows or a bilevel printing plate :~
comprising a substrate having coated thereon a first 2 1 22~
negative-working, non-silver halide, light sensi~ive coating photoinsensitiYe to light at silver halide speeds and a second or top negative-working coating comprising silver halide emulsion.
At a low exposure speed, both a first portion of the plate is exposed image-wise through a positiv~
original with nonimage-wise exposure o~ a second portlon o~ plate. Then, at a high exposure speed second portion ii exposed image-wise through a negative origi~al. The top coat is de~eloped followed by oversll ~xpo6ure of the plate at a high exposure speed. The plate is then treated to remove exposed and unexposed residue of said ~op coating and further treated to remove non-image containing areas of the first coating whereby a printing plate is produced containing images corresponding to the negative and positive originals.
For koth procesies described herein, the order of exposure, i.e~, poiitive origin2l1 Pirst or nega~ive original first is nDt critical. Either original may be exposed first.
The invention also includes a presensitized printing plate for seguentially producing a negative original image and a positive original image on a printing plate employing a singl~ development step. The plate comprises 2~ a substrate having coated th~reon a firit non ~ilver halide, light sensitive coating photoinsensiti~e to light at silver halide exposure speeds and a second or top -~
coating comprising iilver halide emulsion, wherein the irst coating is selected from the group consisting of diazo r~sins, diazide compounds, azide compounds, polymers having alpha, beta un~aturated carbonyl compounds in the main or side chain, and unsaturated monomers photopolymeriæable by addition polymerization.
2 ~
The lithogr~phic print~n~7 plate pr~cur~or o~
pre~ent inverltio3l co~pris~ a ~uppe~ r ~ rate upon which i~ coa~ed a ~ir~t coa~ing comlpri~ g a nonosilvex 5 halîde cs~ting ~en~itive to light alt ::o~tact ~sq?osure speeds and a ~econd or top coatirlg c:omprising a s~lver halid~ emulsion ~enE~itivQ to lighit al: ca~era e~ sur~
~peed8 .
The te~ '~ mera ~p~d~3 ~nd "high sp~3ed' ar~ ~ nter-10 changeably used herein. "Camera ~pQad~ or "high speed"mear~s that the coating i5 su~fici~ntly fa~t, i.e., photo-graphically light sensitive, to be usad in a camera ~uch a~3 a proce~;s camera and embodi~ focusing an origirlal onto the light s~en~itiv~ layer throu~h an image-foc:usi~lg 15 len~. ~ high expo~ure E~pe~d or camQr~ sp2ed co~ting in thQ pr~sent inv~ntion h~b expo~ur~ speed~ betw~en 1 and 2û millijoules per 3quare cen~.imç~ter (m~ but prsîerably about 5 ~j/CDIZ. For camera ~peed or high ~p~d c:c3at~ngs a comparatively lc~w ell~r~ level o~ light 20 i~ all thal: i~ requlred to impinge upon the coating to produce a lighlt induced che~iaal changa in th~3 coating and a corre~ponding photograpPIic ef~ect~ "Contact pe~d'g, sar low ~xpoaur2 8pelBSl a~ u~ad herein, ~e~ns that a light ~ensitiv~ materi~l can b~ exposed through a 25 po~itiv~ or n~g3.tiv~ transpar~ncy original placed in contact with it. Contact ~3pe~d coating~ used in the pre6ant inYention have speedis betwes~n about 200 and 1000 mj/cm2, bllt pr~ferably about 400 mj/cm~. Cor~tac:t expo~ure ~peed or low sps~d coatings re~auire 30 i3ub~t~ntially high~r ~nergy l~vel~3 o~ light to impinsle uporl ~he coating lto produc6l! a ch~r~ic~l change in th~ :
coating and a corresponding photc~raphic ~ffectO
The ~upport or substrate ~or the printing plate prerursor o~ the invention Diay b~ any of tho~ supports 35 or ~ubstratr2s having ~ hydrophilic ~ur~ace that are commonly u~ed as supports in the manu~acture o~ printing plates. Examples include hydrophilic metal plates such as aluminum, composite metal plate6, plastic films, pap~r and the like.
The Pirst coating on the ~ubstrate which compri~es a non silver halide coating ~ensitive to light at contact speeds yields a lipophilic image and includes light sensitive coatings conventionally used in light sensitive lithographic printing plates. The term lipophilic means that the image repels water for wetting in printing and receives oily ink. ~xamples o cumpositions constituting such light sensitive coatlngs are described in U. S.
Patent 4,299,912 and in the patents assigned to Polychrome Corp. and incorporated by reference herein before. They include by example without limitation-Compositions comprising one or more diazo resins;
composikions comprising one or more o-naphthoquinone-diazide compounds; compositions comprising one or more light sensitive azide compounds) compounds comprising one or more polymers containing an alpha, bata unsaturated carbonyl group in the main or s:ide chain thereof; and photopolymeri~able compositions comprising one or more addition polymeri~able unsaturated compounds.
As used herein, by light sensitive ~irst layer or coating capable of being used as th~ light sensitive layer in a negative-working presensitized printing plate is meant a layer which can be coated onto the base and which is sensitive to light such as ultra-violet light and when exposed to such through a negative in the exposed areas undergoes goes a chemical reaction which renders the exposed areas insolubl~ laaving the unexpoeed areas dissoluble. By light sensitive first layer or co~ting capable of being used as the light sansitive layer in a positive-working presensitized printing plate is meant any liyht sensitive composition that is 2~.~2~
~9_ sensitive to light such as ultraviolet light and when ~ exposed to such light undergoes a chemical reaction in the expos~d areas whereby the exposed areas become s41uble and removablP.
A~ example of a positive working resin composition which can be developed with an alkaline solution is one which contains a light sensitive material such as o-naphthoquinonediazide. Examples o~ negative working resin compositions which can be developed following UV
light exposure include polvinylcinnamate, vinyl polymeris containing an aromatic azide group and the li~e. The photographic speed o~ these compounds is too slow ~sr ~
plates sensitized therewith to be o~ camera speed and ~ ~X
thus, as previously ~tated, mo~t presensitized lithoyraphic plates are of contact ipeed.
U. S. Patents 4,483,758 and 4,447,512 incorporated herein by reference, teach nega1ive working co~positions consisting of diazo resin based on diphenyl amine sulfate condensate with formaldehyde an~l isolated as 2-hydroxy-4 methoxy-benzophenone-5-sulfonic acid salt. Also included ~;
are polymers with alpha, beta unsaturated carbonyl groups in the main or side chain.
The top layer or coating o:E the lithographic plate ~ :~
precursor o~ the invention comprises any type of gelatin-silver halide emulsion depending on the original to ~e produced. Silver halide includes silver chloride, silver bromide, silver iodide and mixtures thereof as conventionally employ~d in the art. The average silver halide grain diameter is preferably between O.Ol~i and 5 In oxder to provide a suitable or desired sensiti~ity to the silver halide, the grains thereof can be subject to chemical sensitization, eOg., sul~ur sensitization, reduction sensitization, sensitization ~,"~ , "".~" ~. ~,,.
2~2~
--lo~
using salts of noble metals such as Ir, Rh, Pt, etc., or speGtral sensitizatiQn using ~ensitizing dyes. Silver halides o~ the latent sur~ace image type and inner latent image type can be used. The silver halide emulsion generally contain various additives as known in the art.
The gelatin-silver halide light sensitive emulsion layer i5 provided so that the dry weight is about 1 to about 10 g/mZ, preferably from 2 to 6 g/m2.
The invention comprises a process to prcvide a :~
n bilevel printing plate precursor that can ba developed in one step or stage to produce positive, printahle images from both negative image input and positive image input material. ~
Positive-workin~ Plate ~ith ~egLative-workinq Emulsion ~:
A preferred embodiment comprises a six-step process.
A presensitized printing plate is provided containing a ~irst positive-working light sensitive resin coatingO
The printing plate is then coated with a second coating comprising a negative-working liLght sensitive silver halide emulsion to provide a bileYel plate. The six process step~ are carried on the bilevel plate.
In a first step, a first portion of the printing plate is exposed throuqh a positive original at a high light energy level (about 400 mj/cm2). The exposur~
results in a conversion of a corresponding portion of the silver halide emulsion to latent sil~er image and a conversion of a corresponding portion of the light sensitive r~sin to an alkali solubl~ resin. The unexposed area corresponds with the positive image in both the top ~nd first coating.
In the next step; a second portion of the plate is exposed through a negative original at a substantially - 2~22~ ~
lower light energy 12vel (about 5 mj~cm2) and the positive exp~sed first portion o~ the plate is also exposed to the same low light energy level, thereby blocking or prot~cting the unexposed portion of the f.irst coating in the first portion of the plate. Optionally, the positive exposed first portion of the pla~e can be masked and subsequently exposed to lower light energy level but it is preferred to carry out an overall ~xposure. This step creates a latent image of the neyativ~ original in the emulsion on the second portion : :
of the plate while the unexpos~d portion of the emul~ion on s~id first portion is also expos~d. The low energy level is too low to convert the resin coating.
~: `~ .' The lentire plate is processed in a developer to develop the negative latent image in the emulsion o~ the second portion of the plate and the fogged area of the emulsion of the first portion. The developed negative image is fixed, resultin~ in removal of silver halide in the second portion area while metallic silver in the first and second portions of the~ emulsion remain unchanged. This step provides a silver coating in the top layer protecting the first portion overall and thus the unexposed porkion of the first layer corresponding to the po~itive original image. In a~dition, a silver coating in th~ second portion which corresponds to the neyative original image area covers or protects the ~irst coating from subse~uent expo~ure.
After the development step, the entire area o~ the plate is preferably exposed overall to a high light energy level of about 400 mj/cm2~ The exposur~ results in the conversion or exposure o~ the resin und2rneath the emulsion on the second portion of th plat~ except for that area of the resin directly underneath th~ image produced in the emulsion ~rom the negative exposure.
2 ~
.. ...
Following overall exposure at high exposure speed the emulsion layer i removed by washing or o-ther means well known to those skilled in the art l aving the resin layer containing exposed resin in the first and second portions and unexposed resin corresponding to the positive and negative image in the first and second -portion of the plate. ~
Next, the exposed resin areas which contain, in one ~ .
embodiment, carboxyliG acids produced by exposure to light are removed by alkali treatment leaving only the :
resin containing area~ corresponding to the positive and negative images~ These areas are further processed by means ~nown in the art such as heating to harden (baking), QtC, for printing.
The process can be carried out by first exposing the plate to negative original input followed by positive input. For that option the process is modified to comprise a first image-wise exposing of a first portion of the plate through a negative original with nonimage-wise exposing the second portion at low exposure speed sufficient to expose the second coating only. The nexk st~p comprises image-wise expos:ing the second portion using the positive original at high exposure speed sufficient to expose the first and second coating.
Subsequent processing follows the d2velopment, post-exposure and treatment steps described above.
Neqative-workinq Plate with NeaativP-workinq Emulsio~
Another preferred embodiment of the invention is to employ a presensitized printing plate having a first negative-working light sensitive resin coating. The printing plate is then coated with a second coating comprisin~ a negative-working light sensitive silver halide emulsion to provide a bilevel plate. The process steps in this embodiment are depicted as ~ollows for :~
' ,,:
,~ 2 ~ ~fJ r;~
:
initial optional ~xposure thro~lgh a positi~ve original:
Exposing at a low exposur~ speed both a ~irst portion of thP plate image-wisa through a pQSitiVe original and no~image-wise exposure of a second portion ::
of said plate. This provides a latent image overall on the second coating except for that portion of the ~irst portion corresponding to the positive image.
Next, exposing at a high exposure sp2ed the second portion image-wise through a negative original. This convert~ the first coating as well as converting the second coating to latent silver image, both in an area corxesponding to the negative image.
Following this, the entire plate is processed in a developer to develop the negative latent image in the emulsion of the first portion oiE the plate and the ~ogged area o~ the emulsion of the second portion. Thi~ step provides a silver coating in the top layer protecting the first portion non-image area and thus the unexposed portion of the first layer corr~sponding to the non-image area of the positive original. :rn addition, a ~ilver ~ :~
coating in the second portion overall prot~cts the firi~t coating non-image area from subsequent exposure. -~
A~ter the development step the entire area of the plate is pr~erably ~xposed overall to a high light energy level of about 400 mj/cm2. The exposure results in the conversion or exposure of the resin underneath the ~::
second coating on the first portion of the plate except ~or that non-image ~rea of the resin protected by metallic silver porti~n~ of the second coating.
Following overall exposure at high exposure speed the emulsion layer is removed by washing or other means well known to those skilled in the art leaving thP resin - 2 ~
~14~
layer containing unexposed re~in in the first and second portions and exposed resin corr~sponding to the positive and negative imaye in the ~irst and second portion o~ the ~:
plate.
Next, the unexposed resin ar~as are removed by ~` .
leaving only the re~in containiny areas corresponding to the positive and negative images. These areas are :~
further processed by means known in the art such as heating to harden, etc, for printing.
Here again th~ order of exposure of the plate comprising a negative-working first coat with negative-working top coat can be varied to expose the plate through a negative original fir~t at low exposure speed rather than through a positive original at low expo~ure speed. This variation o~ the process proceecls as follows:
Exposing image-wise at a high exposure speed through a negative original a first por1;ion o~ the plate and then exposing at a low expo~ure speecl both the second portion of said plate image-wise through a positive original and nonimage-wiss exposure of the flrst portion of the plate.
Subsequent proces~ing follows the development, post-exposure and treatment steps described above for the negative-working first coating and negative-working second coating case.
The following Examples 1 4 describe various embodiments o~ the present invention:
. .
Example 1 :
Polychrome positive plate T-40, described in U. S. ~:
paten~s 4,350,753 and 4,283,478, wa~ overcoated by a ::
"roomliyht" handling silver halide negative emul~ion, Polychrome DLC, day light contact emulsion useful under white light conditions. The plate was exposed for 5 :., mj~cm2 in contact with a negative original using a Berkey Ascor exposure frame. Part of the area not covered by the ne~ative was contacted with a positive trangp~rency while the area of the plate previously cov~red by the 5 negative original was maslced to avoid ;econdary exposure. - `
An expo~ure of 400 m~/cm2 was then given to the plate.
The plate was then processed i~ a rapid access silver halide development solution (b~tch developer PRB 127) ~or negative or positive emul~ions, and Polychrome fixer PF200. Th~ plate was then given overall W exposure, silver emulsion was removed by warm water and processed in conventional positive plate chemistry , i.e.
Polychrome's positive developer 3000 and Gum Pcs63~ The plate exhibited excellent positive image both ~rom the negative original portion and positive original portion.
Example 2 Polychroms positive plate known as 7'Posimatte", described in U. S. patents 4,350,753 and 4,~83,478, was overcoated by Polychrome silver halide emulsion PQF. The plate was exposed on the opticOpy Imposer II (Polychrome System Inc.) using negative transparency as originals with exposure ranging from l to lO seconds to the Imposer light source of pulsed Xenon lamps attenuated by a series o~ ~ilters to givs the ~reen portion of the light -~
spectrumO The expo~ed areas were fully masked by masking sheets. The open areas requiring positive transparency :~
input were contacted with the transparency and were given W exposure to fully expose Posimatte. The trans~
parency was rsmoved and the plate was briefly given an overall (visible light~ exposure to uniformly expose the :~:
coating not covered by the previous negative exposure.
The plate was then developed, fixed, re-exposed, emulsion removed and processed in positive plate developer to give a plate bearing positive image oP both negative input and positive input.
2 ~ ~ ~ 8 ~lj '1 Example 3 Polychrame positivQ plate T-40 was overcoated with Polychrome laser scann~r emulsi4n ~SF ~or ion-argon laser and ~ontaining sensitizing dys~. The plate was ~xposed on Gerber Scientific las~r exposing system LE 55 to give text portion of image in~ormation along with a blank expo~ur~ to the area whex~ the picture and graphic elements were to be inserted. The plate was th~n sxposed in contact with a masking sheet with picture and graphic elements pasted in. Following development, fixing, re- -exposure, washing and development, the plate exhibitsd both text and graphic elements ready for high guality printing.
Example ~
Polychrome negative working plate Vistar M, describecl in U. S. patents 4,483,758 and 4,447,512, is overcoated by a room light handling silver halide negative emulsion, DLC. The plate is exposed for 5.0 mj/cm2 in contact with a positive original using a Berkey Ascor exposure frame. Part of t:he area not covered by the positive is contacted with a negative transparency. An exposure of 400 mj/cm2 is given to the plat~, while the area of the plate previously covered by th~ positive original is masked to avoid secondary ~xposure. The plate is then processed in a rapid access silver halide development solution, i.e., PRB127, and further processed as in Example l.
. .
The progress in digital tec~nology enabled printers ;:~
to use digital direct platemaXers. ~igh speed of text ~:
printing provides considerable productivity improvements over thr convention~l analog mode o~ plat~ preparation. :~
In case o the graphics and pictures, however, the requirements for high level of memory and computing ~peed are such that the sy~tem becomes not only costly but slow to generate high quality images at reasonable speed.
2~22~
, ., ,~ .
".................................................................... :
-17~
The bimodal plate and the process proposed not only eliminates such inconvenience~ as additional film making but also improves productivity substantially by allowing various mode of transparenci~s and signals as the original inpu~. In conventional analog contact method, both negative and positive originals can produce equally excellent images. In case of digital application, high speed texts can be la er imaged while pre-prepared qraphics and picture eleme~ts can be contact exposed taking advantages of high speed digital generation of . .
texts and high rate of information transfer of prepared graphics o high memory requirements.
'~'''~.'`
Claims (16)
1. A process for producing a negative original image and a positive original image on a printing plate employing a single stage development step, comprising the steps of;
(a) providing a printing plate comprising a substrate having a first positive-working, non-silver halide, light sensitive coating photoinsensitive to light at silver halide speeds and a second negative-working coating comprising silver halide emulsion;
(b) exposing a first portion of said plate image-wise through a positive original at a high exposure speed sufficient to expose said first coating and second coating;
(c) exposing at a low exposure speed both a second portion of said plate image-wise through a negative original and nonimage-wise exposure of said first portion from step (b);
(d) developing said second coating after step (c);
(e) exposing said plate from step (c) overall at a high exposure speed;
(f) treating said plate after step (e) to remove exposed and unexposed residue of said second coating;
(g) treating said first coating after step (f) to remove non-image containing areas of said first coating whereby a printing plate is produced containing images corresponding to said negative and positive originals.
(a) providing a printing plate comprising a substrate having a first positive-working, non-silver halide, light sensitive coating photoinsensitive to light at silver halide speeds and a second negative-working coating comprising silver halide emulsion;
(b) exposing a first portion of said plate image-wise through a positive original at a high exposure speed sufficient to expose said first coating and second coating;
(c) exposing at a low exposure speed both a second portion of said plate image-wise through a negative original and nonimage-wise exposure of said first portion from step (b);
(d) developing said second coating after step (c);
(e) exposing said plate from step (c) overall at a high exposure speed;
(f) treating said plate after step (e) to remove exposed and unexposed residue of said second coating;
(g) treating said first coating after step (f) to remove non-image containing areas of said first coating whereby a printing plate is produced containing images corresponding to said negative and positive originals.
2. The process of claim 1 including the further step of treating step (g) images corresponding to said negative and positive originals to harden and stabilize them for multiple printing operations.
3. The process of claim 1 wherein step (b) comprises image-wise exposing said first portion using said negative original and nonimage-wise exposing said second portion at low exposure speed sufficient to expose said second coating only; step (c) comprises image-wise exposing said second portion using said positive original at high exposure speed sufficient to expose said first and second coating.
4. The process of claim 1 wherein said first coating comprises o-napthoquinonediazide.
5. The process of claim 1 wherein said low exposure speed is between 1 and 20 mj/cm2.
6. The process of claim 5 wherein said low speed is about 5 mj/cm2.
7. The process of claim 1 wherein said high exposure speed is between 200 and 1000 mj/cm2.
8. The process of claim 7 wherein said speed is about 400 mj/cm2.
9. A process for producing a negative original image and a positive original image on a bilevel printing plate comprising the steps of:
(a) providing a bilevel printing plate comprising a substrate having a first negative-working, non-silver halide, light sensitive coating photoinsensitive to light at silver halide speeds and a second neqative-workine coating comprising silver halide emulsion:
(b) exposing at a low exposure speed both a first portion of said plate image-wise through a positive original and nonimage-wise exposure of a second portion of said plate;
(c) exposing at a high exposure speed said second portion image-wise through a negative original;
(d) developing said second coating after step (c);
(e) exposing said plate from step (c) overall at a high exposure speed;
(f) treating said plate after step (e) to remove exposed and unexposed residue of said top coating;
(g) treating said first coating after step (f) to remove non-image containing areas of said first coating whereby a printing plate is produced containing images corresponding to said negative and positive originals.
(a) providing a bilevel printing plate comprising a substrate having a first negative-working, non-silver halide, light sensitive coating photoinsensitive to light at silver halide speeds and a second neqative-workine coating comprising silver halide emulsion:
(b) exposing at a low exposure speed both a first portion of said plate image-wise through a positive original and nonimage-wise exposure of a second portion of said plate;
(c) exposing at a high exposure speed said second portion image-wise through a negative original;
(d) developing said second coating after step (c);
(e) exposing said plate from step (c) overall at a high exposure speed;
(f) treating said plate after step (e) to remove exposed and unexposed residue of said top coating;
(g) treating said first coating after step (f) to remove non-image containing areas of said first coating whereby a printing plate is produced containing images corresponding to said negative and positive originals.
10. The process of claim 9 including the further step of treating step (g) images corresponding to said negative and positive originals to harden and stabilize them for multiple printing operations.
11. The process of claim 9 wherein said low exposure speed is between 1 and 20 mj/cm2.
12. The process of claim 11 wherein said low speed is about 5 mj/cm2.
13. The process of claim 9 wherein said high exposure speed is between 200 and 1000 mj/cm2.
14. The process of claim 13 wherein said speed is about 400 mj/cm2.
15. The process of claim 9 wherein step (b) comprises exposing image-wise at a high exposure speed through a negative original said second portion and step (c) comprises exposing at a low exposure speed both said first portion of said plate image-wise through a positive original and nonimage-wise exposure of said second portion of said plate.
16. A presensitized printing plate for sequentially producing a negative original image and a positive original image on a printing plate employing a single development step, said plate comprising a substrate having coated thereon a first non-silver halide, light sensitive coating photoinsensitive to light at silver halide speeds and a second or top coating comprising silver halide emulsion, wherein said first coating is selected from the group consisting of phenolic-Novolak resin, o-naphthoquinonediazide, and the ester of 2-diazo-1-naphthol-4 (or-5)-sulfonic acid with a polyhydroxy phenol.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/057,592 | 1993-05-05 | ||
| US08/057,592 US5330875A (en) | 1993-05-05 | 1993-05-05 | Process for producing negative and positive original images on a bilevel printing plate utilizing non-silver halide layer and silver halide overlayer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2122804A1 true CA2122804A1 (en) | 1994-11-06 |
Family
ID=22011557
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002122804A Abandoned CA2122804A1 (en) | 1993-05-05 | 1994-05-03 | Single step developable negative working and positive working printing plate and imaging process |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5330875A (en) |
| EP (1) | EP0623853B1 (en) |
| AT (1) | ATE140804T1 (en) |
| CA (1) | CA2122804A1 (en) |
| DE (1) | DE69400326T2 (en) |
| DK (1) | DK0623853T3 (en) |
| ES (1) | ES2091660T3 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5512420A (en) * | 1995-02-22 | 1996-04-30 | Sun Chemical Corporation | Waterless presensitized plate comprising four layers |
| US5948596A (en) * | 1997-05-27 | 1999-09-07 | Kodak Polychrome Graphics Llc | Digital printing plate comprising a thermal mask |
| US6187510B1 (en) | 1999-03-09 | 2001-02-13 | Kodak Polychrome Graphics Llc | Digital lithographic printing plate and method of making thereof |
| SE516194C2 (en) * | 2000-04-18 | 2001-12-03 | Obducat Ab | Substrate for and process of fabrication of structures |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1187980A (en) * | 1966-10-28 | 1970-04-15 | Ilford Ltd | Presensitised Lithographic Plates. |
| US3635709A (en) * | 1966-12-15 | 1972-01-18 | Polychrome Corp | Light-sensitive lithographic plate |
| BE754743A (en) * | 1969-08-13 | 1971-01-18 | B K T Displays Ltd | PROCESS FOR PREPARING THE CLICHES FOR PHOTOGRAVURE |
| JPS54152502A (en) * | 1978-05-19 | 1979-11-30 | Fuji Photo Film Co Ltd | Photosensitive printing plate material and method of making printing plate from said material |
| JPS5625739A (en) * | 1979-08-07 | 1981-03-12 | Fuji Photo Film Co Ltd | Preparation of printing plate |
| JPS56117241A (en) * | 1980-02-22 | 1981-09-14 | Fuji Photo Film Co Ltd | Photosensitive lithographic printing plate |
| US4348471A (en) * | 1981-06-15 | 1982-09-07 | Polychrome Corporation | Positive acting composition yielding pre-development high visibility image after radiation exposure comprising acid free novolak, diazo oxide and acid sensitive dyestuff |
| US4447512A (en) * | 1982-01-25 | 1984-05-08 | Polychrome Corporation | Method for making a negative working lithographic printing plate |
| JPS5962859A (en) * | 1982-10-04 | 1984-04-10 | Fuji Photo Film Co Ltd | Photoengraving method of photosensitive lithographic printing plate |
| DE3325023A1 (en) * | 1983-07-11 | 1985-01-24 | Hoechst Ag, 6230 Frankfurt | METHOD FOR PRODUCING NEGATIVE COPIES BY MEANS OF A MATERIAL BASED ON 1,2-CHINONDIAZIDES |
| JPS6275638A (en) * | 1985-09-30 | 1987-04-07 | Fuji Photo Film Co Ltd | Photosensitive lightgraphic printing plate |
| ZA872295B (en) * | 1986-03-13 | 1987-09-22 |
-
1993
- 1993-05-05 US US08/057,592 patent/US5330875A/en not_active Expired - Fee Related
-
1994
- 1994-05-03 CA CA002122804A patent/CA2122804A1/en not_active Abandoned
- 1994-05-04 EP EP94107009A patent/EP0623853B1/en not_active Expired - Lifetime
- 1994-05-04 AT AT94107009T patent/ATE140804T1/en not_active IP Right Cessation
- 1994-05-04 DK DK94107009.6T patent/DK0623853T3/en active
- 1994-05-04 DE DE69400326T patent/DE69400326T2/en not_active Expired - Fee Related
- 1994-05-04 ES ES94107009T patent/ES2091660T3/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0623853B1 (en) | 1996-07-24 |
| ATE140804T1 (en) | 1996-08-15 |
| ES2091660T3 (en) | 1996-11-01 |
| EP0623853A1 (en) | 1994-11-09 |
| US5330875A (en) | 1994-07-19 |
| DE69400326T2 (en) | 1997-03-06 |
| DE69400326D1 (en) | 1996-08-29 |
| DK0623853T3 (en) | 1996-11-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4356255A (en) | Photosensitive members and a process for forming patterns using the same | |
| US4123272A (en) | Double-negative positive-working photohardenable elements | |
| CA2065738A1 (en) | A silver halide photographic transfer element and a method for transferring an image from the transfer element to a receptor surface | |
| US4183990A (en) | Step tablet | |
| EP0305599A1 (en) | Halftone image production | |
| GB2065318A (en) | Photosensitive lithographic printing plate precursors and methods of preparing printing plate therefrom | |
| US3578451A (en) | Integral negative type positive photolithographic plate | |
| CA2122804A1 (en) | Single step developable negative working and positive working printing plate and imaging process | |
| JPS6249613B2 (en) | ||
| US4283478A (en) | Light-sensitive material for preparing a lithographic printing plate and a process using the same | |
| EP0185410B1 (en) | Improved process for the formation of a linework or halftone multi-colour colloid pattern | |
| US3249436A (en) | Process for preparing printing plates from photopolymerizable materials by the use of a masking technique | |
| JPS56117241A (en) | Photosensitive lithographic printing plate | |
| EP0194704B1 (en) | Process for the formation of linework or halftone multicolour colloid patterns | |
| EP0130581B1 (en) | Enlargement of photopolymer images in photopolymer mask | |
| US4343876A (en) | Dot-enlargement process for photopolymer litho masks | |
| JPH05204116A (en) | Exfoliative film material | |
| EP0298158B1 (en) | Silver complex diffusion transfer processing | |
| JPS5811943A (en) | Screenless plane printing plate | |
| US4233393A (en) | Silver halidephotosensitive material | |
| US3895946A (en) | Process for producing a lithographic printing plate | |
| EP0094830A1 (en) | Improvements relating to electrophotography | |
| EP0625224B1 (en) | Image carrier for a reprographic image | |
| US4565770A (en) | Process for dot etching acid soluble photopolymerizable elements utilizing chemically soluble pigments | |
| US3814603A (en) | Method for preparing lithographic printing plate |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20000503 |